Origin of life. II. From prebiotic replicators to protocells.

Primitive microvesicles (coacervates, microspheres, marigranules, etc.), free-born in aqueous media, are only protometabolic proteinoids surrounded by an amphiphilic protomembrane. In contrast, surface-born microvesicles could be initiated in the pores of watered rocks providing primary boundaries coated by amphiphilic compounds and acting as sinks for primitive peptides and their coding nucleobases N-P anchored on polyphosphates.

Molecular cloning and expression studies of two divergent alpha-tubulin genes in Neurospora crassa.

Three alpha-tubulin isoforms were previously detected in Neurospora crassa. We have cloned and analysed two alpha-tubulin cDNAs, Tub alpha A and Tub alpha B that encode polypeptides of 453 and 451 amino acids, respectively. The encoded amino acids exhibit an unusual divergence of 35%.

Developmental changes in the(45)Ca (2+) uptake byTrichoderma viride mycelium.

The rate of the(45)Ca(2+) uptake by the submergedTrichoderma viride mycelium increased with the age of the culture from 6 h until a maximum which was reached at about 30 h, and then decreased until the uptake was virtually zero. The decrease in the rate of the(45)Ca(2+) uptake was accompanied by an increase of mycelial mass. The uptake rate could not be reactivated upon substituting the medium for a fresh one, without or with dilution of the mycelium.

Purification of a 47-kDa calmodulin-binding polypeptide as an actin-binding protein from Neurospora crassa.

We have enriched a 47-kDa polypeptide (p47) from Neurospora crassa on the basis of its affinity to calmodulin. The p47 was purified to homogeneity by chromatography on a Mono S cation exchange column and evidence is presented that the polypeptide co-sediments specifically with F-actin. The intracellular distribution of p47 and actin was also examined using indirect double immunofluorescence staining of cells at different stages of development.

A stringent role of F-actin in the ascogonial differentiation of Neurospora crassa fluffy mutant.

Cytochalasin D, an inhibitor of actin polymerization, interferes with ascogonial differentiation in the fertile fluffy mutant of Neurospora crassa. As the total level of actin and its mRNA remain unchanged, this suggests that it is in its microfilamentous form (F-form) that actin is stringently required for female differentiation.